4 files changed, 81 insertions, 415 deletions

diff --git a/gnu/local.mk b/gnu/local.mk
index f118fe44420..f7412d055f6 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -1849,6 +1849,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/mono-mcs-patches-from-5.10.0.patch       \
   %D%/packages/patches/mosaicatcher-unbundle-htslib.patch       \
   %D%/packages/patches/mrrescue-support-love-11.patch           \
+  %D%/packages/patches/mrustc-patches.patch                     \
   %D%/packages/patches/mtools-mformat-uninitialized.patch       \
   %D%/packages/patches/mupen64plus-ui-console-notice.patch      \
   %D%/packages/patches/musl-cross-locale.patch                  \
@@ -2177,7 +2178,6 @@ dist_patch_DATA =						\
   %D%/packages/patches/ruby-mustache-1.1.1-fix-race-condition-tests.patch \
   %D%/packages/patches/ruby-nokogiri.patch                      \
   %D%/packages/patches/ruby-x25519-automatic-fallback-non-x86_64.patch \
-  %D%/packages/patches/rustc-1.54.0-src.patch                   \
   %D%/packages/patches/rust-1.64-fix-riscv64-bootstrap.patch    \
   %D%/packages/patches/rust-1.70-fix-rustix-build.patch \
   %D%/packages/patches/rust-1.78-unwinding-fix.patch            \
diff --git a/gnu/packages/patches/mrustc-patches.patch b/gnu/packages/patches/mrustc-patches.patch
new file mode 100644
index 00000000000..626945e2a12
--- /dev/null
+++ b/gnu/packages/patches/mrustc-patches.patch
@@ -0,0 +1,19 @@
+diff --git a/rustc-1.54.0-src.patch b/rustc-1.54.0-src.patch
+index 088c723a..d322fd0d 100644
+--- a/rustc-1.54.0-src.patch
++++ b/rustc-1.54.0-src.patch
+@@ -302,14 +302,3 @@
+  use self::generic as arch;
+  
+  pub use self::arch::{vec128_storage, vec256_storage, vec512_storage};
+-
+---- src/llvm-project/llvm/include/llvm/Support/Signals.h
+-+++ src/llvm-project/llvm/include/llvm/Support/Signals.h
+-@@ -14,6 +14,7 @@
+- #ifndef LLVM_SUPPORT_SIGNALS_H
+- #define LLVM_SUPPORT_SIGNALS_H
+- 
+-+#include <cstdint>
+- #include <string>
+- 
+- namespace llvm {
diff --git a/gnu/packages/patches/rustc-1.54.0-src.patch b/gnu/packages/patches/rustc-1.54.0-src.patch
deleted file mode 100644
index d322fd0d499..00000000000
--- a/gnu/packages/patches/rustc-1.54.0-src.patch
+++ /dev/null
@@ -1,304 +0,0 @@
-# mrustc is much better at enum packing, so causes almost all of these to be smaller by one pointer
---- compiler/rustc_ast/src/ast.rs
-+++ compiler/rustc_ast/src/ast.rs
-@@ -1075,7 +1075,7 @@ pub struct Expr {
- }
- 
- // `Expr` is used a lot. Make sure it doesn't unintentionally get bigger.
--#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-+#[cfg(all(not(rust_compiler = "mrustc"), target_arch = "x86_64", target_pointer_width = "64"))]
- rustc_data_structures::static_assert_size!(Expr, 104);
- 
- impl Expr {
-@@ -2779,7 +2779,7 @@ pub enum AssocItemKind {
-     MacCall(MacCall),
- }
- 
--#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-+#[cfg(all(not(rust_compiler = "mrustc"), target_arch = "x86_64", target_pointer_width = "64"))]
- rustc_data_structures::static_assert_size!(AssocItemKind, 72);
- 
- impl AssocItemKind {
-@@ -2831,7 +2831,7 @@ pub enum ForeignItemKind {
-     MacCall(MacCall),
- }
- 
--#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-+#[cfg(all(not(rust_compiler="mrustc"),target_arch = "x86_64", target_pointer_width = "64"))]
- rustc_data_structures::static_assert_size!(ForeignItemKind, 72);
- 
- impl From<ForeignItemKind> for ItemKind {
-
---- compiler/rustc_hir/src/hir.rs
-+++ compiler/rustc_hir/src/hir.rs
-@@ -3048,7 +3048,7 @@ impl<'hir> Node<'hir> {
- }
- 
- // Some nodes are used a lot. Make sure they don't unintentionally get bigger.
--#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-+#[cfg(all(not(rust_compiler="mrustc"),target_arch = "x86_64", target_pointer_width = "64"))]
- mod size_asserts {
-     rustc_data_structures::static_assert_size!(super::Block<'static>, 48);
-     rustc_data_structures::static_assert_size!(super::Expr<'static>, 64);
-
---- compiler/rustc_middle/src/mir/interpret/error.rs
-+++ compiler/rustc_middle/src/mir/interpret/error.rs
-@@ -449,7 +449,7 @@ impl dyn MachineStopType {
-     }
- }
- 
--#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-+#[cfg(all(not(rust_compiler="mrustc"), target_arch = "x86_64", target_pointer_width = "64"))]
- static_assert_size!(InterpError<'_>, 64);
- 
- pub enum InterpError<'tcx> {
-
---- compiler/rustc_middle/src/mir/mod.rs
-+++ compiler/rustc_middle/src/mir/mod.rs
-@@ -2200,7 +2200,7 @@ pub enum AggregateKind<'tcx> {
-     Generator(DefId, SubstsRef<'tcx>, hir::Movability),
- }
- 
--#[cfg(target_arch = "x86_64")]
-+#[cfg(all(not(rust_compiler="mrustc"), target_arch = "x86_64"))]
- static_assert_size!(AggregateKind<'_>, 48);
- 
- #[derive(Copy, Clone, Debug, PartialEq, PartialOrd, Eq, TyEncodable, TyDecodable, Hash, HashStable)]
-
---- compiler/rustc_middle/src/thir.rs
-+++ compiler/rustc_middle/src/thir.rs
-@@ -144,7 +144,7 @@ pub enum StmtKind<'tcx> {
- }
- 
- // `Expr` is used a lot. Make sure it doesn't unintentionally get bigger.
--#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-+#[cfg(all(not(rust_compiler="mrustc"), target_arch = "x86_64", target_pointer_width = "64"))]
- rustc_data_structures::static_assert_size!(Expr<'_>, 144);
- 
- /// The Thir trait implementor lowers their expressions (`&'tcx H::Expr`)
-
---- compiler/rustc_mir/src/interpret/operand.rs
-+++ compiler/rustc_mir/src/interpret/operand.rs
-@@ -32,7 +32,7 @@ pub enum Immediate<Tag = ()> {
-     ScalarPair(ScalarMaybeUninit<Tag>, ScalarMaybeUninit<Tag>),
- }
- 
--#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-+#[cfg(all(not(rust_compiler = "mrustc"), target_arch = "x86_64", target_pointer_width = "64"))]
- rustc_data_structures::static_assert_size!(Immediate, 56);
- 
- impl<Tag> From<ScalarMaybeUninit<Tag>> for Immediate<Tag> {
-@@ -87,7 +87,7 @@ pub struct ImmTy<'tcx, Tag = ()> {
-     pub layout: TyAndLayout<'tcx>,
- }
- 
--#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-+#[cfg(all(not(rust_compiler = "mrustc"), target_arch = "x86_64", target_pointer_width = "64"))]
- rustc_data_structures::static_assert_size!(ImmTy<'_>, 72);
- 
- impl<Tag: Copy> std::fmt::Display for ImmTy<'tcx, Tag> {
-
---- compiler/rustc_mir/src/interpret/place.rs
-+++ compiler/rustc_mir/src/interpret/place.rs
-@@ -88,7 +88,7 @@ pub enum Place<Tag = ()> {
-     Local { frame: usize, local: mir::Local },
- }
- 
--#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-+#[cfg(all(not(rust_compiler = "mrustc"), target_arch = "x86_64", target_pointer_width = "64"))]
- rustc_data_structures::static_assert_size!(Place, 64);
- 
- #[derive(Copy, Clone, Debug)]
-@@ -97,7 +97,7 @@ pub struct PlaceTy<'tcx, Tag = ()> {
-     pub layout: TyAndLayout<'tcx>,
- }
- 
--#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-+#[cfg(all(not(rust_compiler = "mrustc"), target_arch = "x86_64", target_pointer_width = "64"))]
- rustc_data_structures::static_assert_size!(PlaceTy<'_>, 80);
- 
- impl<'tcx, Tag> std::ops::Deref for PlaceTy<'tcx, Tag> {
-
-#
-# Disable std_detect's detection logic (use the same logic as miri)
-#
---- library/stdarch/crates/std_detect/src/detect/mod.rs
-+++ library/stdarch/crates/std_detect/src/detect/mod.rs
-@@ -86,7 +86,7 @@ mod bit;
- mod cache;
- 
- cfg_if! {
--    if #[cfg(miri)] {
-+    if #[cfg(any(miri, rust_compiler = "mrustc"))] {
-         // When running under miri all target-features that are not enabled at
-         // compile-time are reported as disabled at run-time.
-         //
-
-#
-# Disable crc32fast's use of stdarch
-#
---- vendor/crc32fast/src/specialized/mod.rs
-+++ vendor/crc32fast/src/specialized/mod.rs
-@@ -1,5 +1,6 @@
- cfg_if! {
-     if #[cfg(all(
-+        not(rust_compiler = "mrustc"),
-         crc32fast_stdarchx86,
-         any(target_arch = "x86", target_arch = "x86_64")
-     ))] {
-
-#
-# Backport which is required to support arm64 on macOS 12
-# See: https://github.com/alexcrichton/curl-rust/commit/0aea09c428b9bc2bcf46da0fc33959fe3f03c74a
-#
---- vendor/curl/src/lib.rs
-+++ vendor/curl/src/lib.rs
-@@ -82,6 +82,9 @@ pub mod easy;
- pub mod multi;
- mod panic;
- 
-+#[cfg(test)]
-+static INITIALIZED: std::sync::atomic::AtomicBool = std::sync::atomic::AtomicBool::new(false);
-+
- /// Initializes the underlying libcurl library.
- ///
- /// The underlying libcurl library must be initialized before use, and must be
-@@ -102,46 +105,62 @@ pub fn init() {
-     /// Used to prevent concurrent or duplicate initialization.
-     static INIT: Once = Once::new();
- 
--    /// An exported constructor function. On supported platforms, this will be
--    /// invoked automatically before the program's `main` is called.
--    #[cfg_attr(
--        any(target_os = "linux", target_os = "freebsd", target_os = "android"),
--        link_section = ".init_array"
--    )]
--    #[cfg_attr(target_os = "macos", link_section = "__DATA,__mod_init_func")]
--    #[cfg_attr(target_os = "windows", link_section = ".CRT$XCU")]
--    static INIT_CTOR: extern "C" fn() = init_inner;
-+    INIT.call_once(|| {
-+        #[cfg(need_openssl_init)]
-+        openssl_probe::init_ssl_cert_env_vars();
-+        #[cfg(need_openssl_init)]
-+        openssl_sys::init();
-+
-+        unsafe {
-+            assert_eq!(curl_sys::curl_global_init(curl_sys::CURL_GLOBAL_ALL), 0);
-+        }
-+
-+        #[cfg(test)]
-+        {
-+            INITIALIZED.store(true, std::sync::atomic::Ordering::SeqCst);
-+        }
-+
-+        // Note that we explicitly don't schedule a call to
-+        // `curl_global_cleanup`. The documentation for that function says
-+        //
-+        // > You must not call it when any other thread in the program (i.e. a
-+        // > thread sharing the same memory) is running. This doesn't just mean
-+        // > no other thread that is using libcurl.
-+        //
-+        // We can't ever be sure of that, so unfortunately we can't call the
-+        // function.
-+    });
-+}
- 
-+/// An exported constructor function. On supported platforms, this will be
-+/// invoked automatically before the program's `main` is called. This is done
-+/// for the convenience of library users since otherwise the thread-safety rules
-+/// around initialization can be difficult to fulfill.
-+///
-+/// This is a hidden public item to ensure the symbol isn't optimized away by a
-+/// rustc/LLVM bug: https://github.com/rust-lang/rust/issues/47384. As long as
-+/// any item in this module is used by the final binary (which `init` will be)
-+/// then this symbol should be preserved.
-+#[used]
-+#[doc(hidden)]
-+#[cfg_attr(
-+    any(target_os = "linux", target_os = "freebsd", target_os = "android"),
-+    link_section = ".init_array"
-+)]
-+#[cfg_attr(target_os = "macos", link_section = "__DATA,__mod_init_func")]
-+#[cfg_attr(target_os = "windows", link_section = ".CRT$XCU")]
-+pub static INIT_CTOR: extern "C" fn() = {
-     /// This is the body of our constructor function.
-     #[cfg_attr(
-         any(target_os = "linux", target_os = "android"),
-         link_section = ".text.startup"
-     )]
--    extern "C" fn init_inner() {
--        INIT.call_once(|| {
--            #[cfg(need_openssl_init)]
--            openssl_sys::init();
--
--            unsafe {
--                assert_eq!(curl_sys::curl_global_init(curl_sys::CURL_GLOBAL_ALL), 0);
--            }
--
--            // Note that we explicitly don't schedule a call to
--            // `curl_global_cleanup`. The documentation for that function says
--            //
--            // > You must not call it when any other thread in the program (i.e.
--            // > a thread sharing the same memory) is running. This doesn't just
--            // > mean no other thread that is using libcurl.
--            //
--            // We can't ever be sure of that, so unfortunately we can't call the
--            // function.
--        });
-+    extern "C" fn init_ctor() {
-+        init();
-     }
- 
--    // We invoke our init function through our static to ensure the symbol isn't
--    // optimized away by a bug: https://github.com/rust-lang/rust/issues/47384
--    INIT_CTOR();
--}
-+    init_ctor
-+};
- 
- unsafe fn opt_str<'a>(ptr: *const libc::c_char) -> Option<&'a str> {
-     if ptr.is_null() {
-@@ -158,3 +177,20 @@ fn cvt(r: curl_sys::CURLcode) -> Result<(), Error> {
-         Err(Error::new(r))
-     }
- }
-+
-+#[cfg(test)]
-+mod tests {
-+    use super::*;
-+
-+    #[test]
-+    #[cfg(any(
-+        target_os = "linux",
-+        target_os = "macos",
-+        target_os = "windows",
-+        target_os = "freebsd",
-+        target_os = "android"
-+    ))]
-+    fn is_initialized_before_main() {
-+        assert!(INITIALIZED.load(std::sync::atomic::Ordering::SeqCst));
-+    }
-+}
-
-# PPV-Lite also needs to know that we're pretending to be miri
---- vendor/ppv-lite86/src/lib.rs
-+++ vendor/ppv-lite86/src/lib.rs
-@@ -9,14 +9,14 @@ mod soft;
- mod types;
- pub use self::types::*;
- 
--#[cfg(all(feature = "simd", target_arch = "x86_64", not(miri)))]
-+#[cfg(all(feature = "simd", target_arch = "x86_64", not(miri), not(rust_compiler = "mrustc")))]
- pub mod x86_64;
--#[cfg(all(feature = "simd", target_arch = "x86_64", not(miri)))]
-+#[cfg(all(feature = "simd", target_arch = "x86_64", not(miri), not(rust_compiler = "mrustc")))]
- use self::x86_64 as arch;
- 
--#[cfg(any(miri, not(all(feature = "simd", any(target_arch = "x86_64")))))]
-+#[cfg(any(miri, rust_compiler = "mrustc", not(all(feature = "simd", any(target_arch = "x86_64")))))]
- pub mod generic;
--#[cfg(any(miri, not(all(feature = "simd", any(target_arch = "x86_64")))))]
-+#[cfg(any(miri, rust_compiler = "mrustc", not(all(feature = "simd", any(target_arch = "x86_64")))))]
- use self::generic as arch;
- 
- pub use self::arch::{vec128_storage, vec256_storage, vec512_storage};
diff --git a/gnu/packages/rust.scm b/gnu/packages/rust.scm
index d5da35b5afc..e55b91b1fe4 100644
--- a/gnu/packages/rust.scm
+++ b/gnu/packages/rust.scm
@@ -128,9 +128,9 @@
 
 ;;; Note: mrustc's only purpose is to be able to bootstap Rust; it's designed
 ;;; to be used in source form.
-(define %mrustc-commit "b6754f574f8846eb842feba4ccbeeecb10bdfacc")
+(define %mrustc-commit "5e01a76097265f4bb27b18885b9af3f2778180f9")
 (define %mrustc-source
-  (let* ((version "0.10.1")
+  (let* ((version "0.11.0")
          (commit %mrustc-commit)
          (revision "1")
          (name "mrustc"))
@@ -138,11 +138,11 @@
       (method git-fetch)
       (uri (git-reference
             (url "https://github.com/thepowersgang/mrustc")
-            (commit (string-append "v" version))))
-      (file-name (git-file-name name version))
+            (commit %mrustc-commit)))
+      (file-name (git-file-name name (git-version version revision commit)))
       (sha256
-       (base32
-        "0rqiif7rb5hg6ik3i1flldj311f014q4n9z8wb50cs8kspjz32di"))
+       (base32 "1yyjfl1z6d5r9sv7zl90kqyjw1lqd2cqzwh2syi7yvrpslhihrhy"))
+      (patches (search-patches "mrustc-patches.patch"))
       (modules '((guix build utils)))
       (snippet
        '(begin
@@ -150,7 +150,10 @@
           ;; by disabling debug by default.
           (substitute* (find-files "." "Makefile")
             (("LINKFLAGS := -g") "LINKFLAGS :=")
-            (("-g ") "")))))))
+            (("-g ") ""))
+          ;; Don't use the vendored openssl sources.
+          (substitute* "minicargo.mk"
+            (("--features vendored-openssl") "")))))))
 
 ;;; Rust 1.54 is special in that it is built with mrustc, which shortens the
 ;;; bootstrap path.
@@ -177,26 +180,24 @@
            ;; Also remove the bundled (mostly Windows) libraries.
            ;; find vendor -not -type d -exec file {} \+ | grep PE32
            (for-each delete-file
-                     (find-files "vendor" "\\.(a|dll|exe|lib)$"))))
-       (patches (search-patches "rustc-1.54.0-src.patch"))
-       (patch-flags '("-p0"))))         ;default is -p1
+                     (find-files "vendor" "\\.(a|dll|exe|lib)$"))
+           ;; Adjust some sources for llvm-13, see llvm commit
+           ;; acce401068e78a8c5dc9e06802111ffad3da763f
+           (substitute* (find-files "." "powerpc64le_unknown_linux_gnu.rs")
+             (("e-m:e-i64:64-n32:64-v256:256:256-v512:512:512")
+              "e-m:e-i64:64-n32:64-S128-v256:256:256-v512:512:512"))))))
     (outputs '("out" "cargo"))
     (properties '((hidden? . #t)
                   (timeout . 129600)          ;36 hours
                   (max-silent-time . 18000))) ;5 hours (for armel)
     (build-system gnu-build-system)
     (inputs
-     `(("bash-minimal" ,bash-minimal)
-       ,@(if (or (target-ppc64le?)
-                 (target-riscv64?))
-             `(("clang" ,clang-13))
-             `())
-       ("llvm" ,llvm-13)
-       ("openssl" ,openssl-1.1)
-       ("zlib" ,zlib)))
+     (list bash-minimal
+           llvm-13
+           openssl-1.1
+           zlib))
     (native-inputs
      `(("pkg-config" ,pkg-config)
-       ;; Required for the libstd sources.
        ("mrustc-source" ,%mrustc-source)))
     (arguments
      `(#:imported-modules ,%cargo-utils-modules ;for `generate-all-checksums'
@@ -207,85 +208,49 @@
        ;; Rust's own .so library files are not found in any RUNPATH, but
        ;; that doesn't seem to cause issues.
        #:validate-runpath? #f
-       ;; We currently see race conditions between various dependant crates.
-       ;; TODO: Re-evaluate after moving to a more recent mrustc.
-       #:parallel-build? #f
        #:make-flags
-       (list ,(string-append "RUSTC_TARGET="
-                             (platform-rust-target
-                               (lookup-platform-by-target-or-system
-                                 (or (%current-target-system)
-                                     (%current-system)))))
-             ,(string-append "RUSTC_VERSION=" version)
-             ,(string-append "MRUSTC_TARGET_VER="
-                             (version-major+minor version))
-             ;; mrustc expects a C11 compatible compiler. Use the default
-             ;; C language dialect from the GCC-10 compiler.
-             ;; This is necessary for some architectures.
-             "CFLAGS=-std=gnu11"
-             "OUTDIR_SUF=")           ;do not add version suffix to output dir
+       ,#~(let ((source #$(package-source this-package)))
+            (list (string-append "RUSTC_TARGET="
+                                 #$(platform-rust-target
+                                     (lookup-platform-by-target-or-system
+                                       (or (%current-target-system)
+                                           (%current-system)))))
+                  (string-append "RUSTC_VERSION=" #$version)
+                  (string-append "MRUSTC_TARGET_VER="
+                                 #$(version-major+minor version))
+                  (string-append "RUSTC_SRC_TARBALL=" source)
+                  "OUTDIR_SUF="))       ;do not add version suffix to output dir
        #:phases
        (modify-phases %standard-phases
-         ,@(if (target-ppc64le?)
-               `((add-after 'unpack 'patch-sources-for-newer-llvm
-                   (lambda _
-                     ;; Adjust some sources for llvm-13, see llvm commit
-                     ;; acce401068e78a8c5dc9e06802111ffad3da763f
-                     (substitute* (find-files "." "powerpc64le_unknown_linux_gnu.rs")
-                       (("e-m:e-i64:64-n32:64-v256:256:256-v512:512:512")
-                        "e-m:e-i64:64-n32:64-S128-v256:256:256-v512:512:512")))))
-               '())
-         (add-after 'unpack 'setup-mrustc-sources
-           (lambda* (#:key inputs #:allow-other-keys)
-             (copy-recursively (assoc-ref inputs "mrustc-source") "../mrustc")
-             ;; The Makefile of mrustc expects the sources directory of rustc
-             ;; to be at this location, and it simplifies things to make it
-             ;; so.
-             (symlink (getcwd)
-                      (string-append "../mrustc/rustc-" ,version "-src"))
-             (with-output-to-file "dl-version"
-               (lambda _
-                 (format #t "~a~%"
-                         ,version)))))
-         (add-after 'setup-mrustc-sources 'patch-makefiles
+         (replace 'unpack
+           (lambda* (#:key source inputs #:allow-other-keys)
+             ((assoc-ref %standard-phases 'unpack)
+              #:source (assoc-ref inputs "mrustc-source"))))
+         (add-after 'unpack 'patch-makefiles
            ;; This disables building the (unbundled) LLVM.
-           (lambda* (#:key inputs parallel-build? #:allow-other-keys)
-             (let ((llvm (assoc-ref inputs "llvm")))
-               (with-directory-excursion "../mrustc"
-                 (substitute* '("minicargo.mk"
-                                "run_rustc/Makefile")
-                   ;; Use the system-provided LLVM.
-                   (("LLVM_CONFIG [:|?]= .*")
-                    (string-append "LLVM_CONFIG := " llvm "/bin/llvm-config\n")))
-                 (substitute* "minicargo.mk"
-                   ;; Do not try to fetch sources from the Internet.
-                   (("@curl.*") "")
-                   (("\\$\\(MINICARGO\\) \\$\\(RUSTC_SRC_DL\\)")
-                    "$(MINICARGO)"))
-                 (substitute* "Makefile"
-                   ;; Patch date and git obtained version information.
-                   ((" -D VERSION_GIT_FULLHASH=.*")
-                    (string-append
-                     " -D VERSION_GIT_FULLHASH=\\\"" ,%mrustc-commit "\\\""
-                     " -D VERSION_GIT_BRANCH=\\\"master\\\""
-                     " -D VERSION_GIT_SHORTHASH=\\\""
-                     ,(string-take %mrustc-commit 7) "\\\""
-                     " -D VERSION_BUILDTIME="
-                     "\"\\\"Thu, 01 Jan 1970 00:00:01 +0000\\\"\""
-                     " -D VERSION_GIT_ISDIRTY=0\n")))
-                 (substitute* "run_rustc/Makefile"
-                   ;; Patch the shebang of a generated wrapper for rustc
-                   (("#!/bin/sh")
-                    (string-append "#!" (which "sh"))))
-                 (substitute* "run_rustc/rustc_proxy.sh"
-                   (("#!/bin/sh")
-                    (string-append "#!" (which "sh"))))))))
-         (add-after 'patch-generated-file-shebangs 'patch-cargo-checksums
-           (lambda _
-             (substitute* "Cargo.lock"
-               (("(checksum = )\".*\"" all name)
-                (string-append name "\"" ,%cargo-reference-hash "\"")))
-             (generate-all-checksums "vendor")))
+           (lambda* (#:key inputs #:allow-other-keys)
+             (substitute* '("minicargo.mk"
+                            "run_rustc/Makefile")
+               ;; Use the system-provided LLVM.
+               (("LLVM_CONFIG [:|?]= .*")
+                (string-append "LLVM_CONFIG := "
+                               (search-input-file inputs "/bin/llvm-config") "\n")))
+             (substitute* "Makefile"
+               ;; Patch date and git obtained version information.
+               ((" -D VERSION_GIT_FULLHASH=.*")
+                (string-append
+                 " -D VERSION_GIT_FULLHASH=\\\"" ,%mrustc-commit "\\\""
+                 " -D VERSION_GIT_BRANCH=\\\"master\\\""
+                 " -D VERSION_GIT_SHORTHASH=\\\""
+                 ,(string-take %mrustc-commit 7) "\\\""
+                 " -D VERSION_BUILDTIME="
+                 "\"\\\"Thu, 01 Jan 1970 00:00:01 +0000\\\"\""
+                 " -D VERSION_GIT_ISDIRTY=0\n")))
+             (substitute* '("run_rustc/Makefile"
+                            "run_rustc/rustc_proxy.sh")
+               ;; Patch the shebang of a generated wrapper for rustc
+               (("#!/bin/sh")
+                (string-append "#!" (which "sh"))))))
          (add-before 'configure 'configure-cargo-home
            (lambda _
              (let ((cargo-home (string-append (getcwd) "/.cargo")))
@@ -293,12 +258,8 @@
                (setenv "CARGO_HOME" cargo-home))))
          (replace 'configure
            (lambda _
-             ,@(if (or (target-ppc64le?)
-                       (target-riscv64?))
-                   `((setenv "CC" "clang")
-                     (setenv "CXX" "clang++"))
-                   `((setenv "CC" "gcc")
-                     (setenv "CXX" "g++")))
+             (setenv "CC" "gcc")
+             (setenv "CXX" "g++")
              ;; The Guix LLVM package installs only shared libraries.
              (setenv "LLVM_LINK_SHARED" "1")
              ;; rustc still insists on having 'cc' on PATH in some places
@@ -314,7 +275,6 @@
                                   1)))
                ;; Adapted from:
                ;; https://github.com/dtolnay/bootstrap/blob/master/build-1.54.0.sh.
-               (chdir "../mrustc")
                ;; Use PARLEVEL since both minicargo and mrustc use it
                ;; to set the level of parallelism.
                (setenv "PARLEVEL" (number->string job-count))
@@ -335,15 +295,6 @@
                (apply invoke "make" "-f" "minicargo.mk" "output/rustc"
                       make-flags)
 
-               ;; We can to continue the build with gcc after building rustc.
-               ;; librustc_driver.so undefined reference to
-               ;; `llvm::cfg::Update<llvm::BasicBlock*>::dump() const'
-               ,@(if (or (target-ppc64le?)
-                         (target-riscv64?))
-                     `((setenv "CC" "gcc")
-                       (setenv "CXX" "g++"))
-                     `())
-
                (display "Building cargo...\n")
                (apply invoke "make" "-f" "minicargo.mk" "output/cargo"
                       make-flags)